Effect of canal blocking on biodiversity of degraded peatlands: Insight from West Kalimantan

PLOS One | https://doi.org/10.1371/journal.pone.0334014 October 8, 2025 7 / 23 Results Wildlife attributes Species richness was notably higher in August compared to May, with 80 species observed in May and 89 species in August across all habitats (Table 2). In both surveys, disturbed peat forest had the highest species count, while estate crop had the lowest. Examining the distribution of data from each transect, less disturbed peat forest and disturbed peat forest consistently exhibited a wider range of species richness compared to estate crop and disturbed wet shrub. More- over, based on the index calculations, Menhinick’s and Margalef’s Richness Indices indicated lower species richness in May, which increased in August across all habitats. Overall, both indices highlighted that less disturbed peat forest and disturbed peat forest had greater species richness compared to estate crop and disturbed wet shrub. Pielou’s Evenness Index, ranging from 0 to 1, indicates the level of evenness within a habitat, with higher values signi- fying greater evenness. In general, forested habitat are recognized for their higher evenness compared to estate crop and disturbed wet shrub. The elevated evenness index values in forested habitats suggest a lack of dominance by any single species, aligning with the findings of the Berger Parker Dominance Index. This index, varying from 0 to 1, reflects domi- nance, with larger values indicating greater dominance. Analysis reveals that estate crop is dominated by a few species

in both months, while the opposite occurs in less disturbed peat forest which consistently had lower dominance. Although disturbed wet shrub exhibited low dominance values in May, these values increased in August, while disturbed peat forest displayed a decrease in dominance over the same period. We used the Shannon and Simpson Diversity Indices across all four habitats. Overall, forested habitats exhibited greater diversity indices compared to non-forested habitats. Less disturbed and disturbed peat forests consistently maintained Shannon Diversity values above 3 in both May and August, while disturbed wet shrub displayed values of 3.11 in May, dropping to 2.76 in August. Estate crop consistently exhibited Shannon Diversity Index values below 3 in both months. There were distinct trends observed in Shannon Diversity Index values: forested habitats experienced an increase in values after the August resurvey, whereas non-forested habitats exhibited a decline. Similar trends were observed in Simpson Diversity Index values, with forested habitats maintaining consistent values while estate crop and disturbed wet shrub exhibited lower values in August compared to May. Following the computation of indices for each habitat, we conducted a comprehensive comparison test to ascertain significant differences between them. The p-values associated with wildlife individual count and species richness indicated no significant differences among the habitats. However, other indices such as Menhinick’s Species Richness, Margalef’s

Species Richness Pielou’s Evennes, Berger Parker Dominance, Shannon Diversity, and Simpson Diversity indicated statistically significant variations. Post-hoc analysis revealed that less disturbed and disturbed peat forests exhibited Table 2. Wildlife attributes at each habitat type. Indices 1st Survey (May) 2nd Survey (August) LF DF EC DW LF DF EC DW Number of Individuals 155 146 190 184 128 135 149 131 Species Richness 37 40 28 35 39 40 27 33 Menhinick’s Species Richness 2.97 3.31 1.96 2.58 3.45 3.44 2.13 2.88 Margalef’s Species Richness 7.14 7.83 5.15 6.52 7.83 7.95 5.20 6.56 Pielou’s Evennes 0.90 0.87 0.81 0.87 0.89 0.90 0.78 0.79 Berger Parker Domince 0.11 0.18 0.29 0.14 0.12 0.10 0.33 0.25 Shannon Diversity 3.23 3.19 2.67 3.11 3.25 3.33 2.53 2.76 Simpson Diversity 0.95 0.94 0.89 0.94 0.95 0.96 0.86 0.89 LF: less disturbed forest, DF: disturbed forest, EC: estate crop, and DS: disturbed wet shrub. https://doi.org/10.1371/journal.pone.0334014.t002